Sorghum & Green Economics

By David Kattenburg

Everything we humans understand about life and the universe began with observations through glass lenses, polished by the likes of Van Leeuwenhoek, Hooke, Huygens, and Galileo. Microscopes and telescopes revealing inner and outer worlds.

Now, in an agronomy lab in Montpellier, France, scientists are devising new imaging techniques that revolutionize our understanding of the secret lives of plants. The potential spin-offs for global green economies are huge. Listen to the story here:

Magnetic resonance imaging, “epifluorescence” microscopy and vertical (versus conventional horizontal) imaging — in the hands of Jean-Luc Verdeil and his colleagues at the Center for International Cooperation & Agronomic Development Research (CIRAD), in Montpellier, France — are revealing how rice plants grow and conserve water; how tea and grapes manufacture those tannins we humans so highly appreciate, and how niche superstar sorghum can be used to build cardboard, concrete, cars or houses — strong and light, and with lower CO2 emission costs than fossil fuels.

Jean-Luc Verdeil

Verdeil’s team is particularly pleased with their vertical plant imaging setup. In conventional microscopy, a biological sample lies flat on a glass slide. But roots grow down and stems up! An innovative system designed by Verdeil and his group is enabling plants to be observed au naturel — growing as they please. The setup is unique, and venerable microscope maker Zeiss is investigating the possibility of marketing it.

It’s “a dream for plant scientists,” says Verdeil, as he shows me a picnic-style setup that maintains optimal humidity for plant growth, and a prototype container, produced with a 3-D printer, in which plants grow vertically as they’re imaged.

Jean-Luc Verdeil and warm, moist air generator

Meanwhile, in a sun-drenched field just outside Montpellier, Verdeil and his team are cultivating sorghum, an exceptionally diverse species they see as a star in the emerging “green economy.”

The world’s half dozen sorghum races are all descended from an ancestral African strain with an extremely tall, strong stalk. With the Green Revolution, shorter strains of sorghum were bred for grain productivity — grain for both livestock feed and human food.

Geneticist David Pot

Tall, biomass-rich sorghum and shorter, grain-packed sorghum are both being grown in CIRAD’s fields outside Montpellier. Geneticist David Pot is cataloging dozens of different sorghum “phenotypes” — observable traits such as stalk strength, biomass production, grain production, drought resistance and so on — and pinpointing the genes linked to those traits.

Not all phenotypes can be observed in a farm field, even with the sharpest eye. Some, like the composition of lignin in the stem, or the presence of water conservation structures inside plant cells, can only be revealed with the aid of advanced imaging techniques.

Researcher Frederic Gatineau, pointing to an MRI image of a water node in a sorghum stem.

Back in the lab, Verdeil recalls observing the organization of water in sorghum stems for the first time ever using magnetic resonance imaging (It was a student who first noted it). One expert couldn’t believe his eyes, and said it wasn’t possible.

Moving from lab to farm field, then back to the lab, is what researchers like Jean-Luc Verdeil, David Pot and colleagues love the most. Listen to them here.